"We don't have information on specifically what caused it in that lake," says Delson. "There are a variety of sources of mercury, sometimes from older mining operations. There are also issues from atmospheric deposition - there's mercury in the air."

Mercury poisoning can damage the brain and nervous system.

Delson says men and older women can eat black bass from the reservoir but should limit their consumption to one serving per week. The advisory is one of more than 80 in place for waterways throughout the state.